1. Field of the Invention
The present disclosure relates to an etching method and an etching apparatus.
2. Description of the Related Art
In order to achieve higher level of miniaturization of semiconductor devices, a critical dimension (CD) obtained by microprocessing with the conventional photolithography needs to be further reduced. For this purpose, EUV (Extreme Ultraviolet) as a next-generation exposure technology is under development. In EUV, since a very short wavelength of, e.g., about 13.5 nm is used, a wavelength of a EUV light source is remarkably shorter than a wavelength of a conventional UV light source. Accordingly, there is a technical barrier to mass production, and a problem such as a longer light exposure time is yet to be solved. Thus, it is required to develop a manufacturing method for a further miniaturized semiconductor device before developing the next-generation exposure technology of EUV.
In this regard, in Patent Document 1, attention is brought to self-assembled block copolymer (BCP) as one of self-assembled materials capable of forming organized patterns by themselves. Specifically, a block copolymer layer, which includes a block copolymer containing at least two polymer block components A and B that are not mixed with each other, is coated on a base layer. Thereafter, as heat-treatment (annealing) is performed, the polymer block components A and B are phase-separated by themselves. With this, a self-assembled pattern of components A and B is formed on a surface of a substrate. Further, in Patent Document 2, in order to achieve miniaturization equal to or less than about 22 nm, there is proposed using a self-assembled pattern of a block copolymer as a via forming method for obtaining an appropriate uniform CD (critical dimension) at a narrower pitch.
As mentioned above, a dimension of the structural unit within the self-assembled pattern of the block copolymer is typically within 10 nanometers order which has been very difficult to achieve in the conventional photolithography.
However, it is difficult to appropriately selectively remove such a fine structural. It means that if one of the structural unit is removed by etching, a processing accuracy error by etching may become greater than a self-assembly error in, e.g., CD value of an opening. As a result, non-uniformity in the dimension of a finally obtained etching pattern as a mask may be outside an allowable range.    Patent Document 1: Japanese Patent Laid-open Publication No. 2007-208255    Patent Document 2: Japanese Patent Laid-open Publication No. 2010-269304